Mediastinitis in patients undergoing cardiopulmonary bypass: risk analysis and midterm results.
BACKGROUND
Deep sternal wound infection (mediastinitis) occurred in 21 out of 4043 consecutive patients who underwent a cardiopulmonary bypass procedure (incidence of 0.4%).


METHODS
Clinical characteristics of patients who developed mediastinitis (group I) were compared to those of patients who had no mediastinal infection (group II).


RESULTS
Hospital mortality was significantly higher in group I (14% vs 3.8%) (p<0.001). Mean hospital stay was longer in group I (36 days vs 7 days) (p<0.001). Multivariate analysis identified the following variables as significant risk factors for developing postoperative mediastinitis: diabetes; relative risk (RR)=3.02, 95% confidence limits (CL)=1.68-5.45, resternotomy for bleeding: RR=5.43, CL=1.85-15.92, associated leg wound infections; RR=16.55, CL=5.32-51.49, the need for 3 or more units of blood transfusion; RR=2.48, CL=1.82-3.39, obesity; RR 4.96, CL 2-12.25. Group I patients were categorised according to a recently proposed classification for mediastinitis (reference 1). Type I (n=17), mediastinitis presenting within 2 weeks following surgery in the absence of risk factors. Type II (n=2), mediastinitis presenting at 2-6 weeks following surgery in the absence of risk factors. Type IIIA (n=2), mediastinitis type I in the presence of one or more risk factor(s). Wound debridement and closed mediastinal irrigation was performed in 19 patients; 15 cases with type I, 2 with type II, and 2 with type IIIA. Primary closure without irrigation was performed in 2 type I patients. The primary intervention failed in 3 patients, two of whom died. A third patient died 4 weeks after an apparently successful treatment of type I mediastinitis. Midterm follow-up (mean of 18 months) of 18 patients showed that 16 patients were alive and well, there was one late death, and one patient had chronic wound pain.


CONCLUSIONS
Diabetes, obesity, associated leg-wound infection, and the need for repeated blood transfusions are associated with high risk of mediastinitis. Closed mediastinal irrigation for mediastinitis type I can yield satisfactory functional and cosmetic midterm results.
El Oakley
R
R
Department of Cardiac Surgery, London Chest Hospital.
Paul
E
E
Wong
P S
PS
Yohana
A
A
Magee
P
P
Walesby
R
R
Wright
J
J
D000368:Aged; D002315:Cardiopulmonary Bypass; D003646:Debridement; D005260:Female; D006331:Heart Diseases / Q000601:surgery; D006801:Humans; D008297:Male; D008480:Mediastinitis / Q000209:etiology* / Q000628:therapy; D008875:Middle Aged; D012307:Risk Factors; D013530:Surgical Wound Infection / Q000209:etiology* / Q000628:therapy; D007507:Therapeutic Irrigation